A motor driver for driving a motor generates a motor drive voltage in an inverter portion and supplies the motor drive voltage to the motor. Generally, an AC voltage outputted from a power supply is smoothed and is thereafter supplied to the inverter portion.
As a technique for smoothing the voltage from the power source, a technique that utilizes smoothing capacitors that are connected in parallel to the power supply is often used as disclosed in Japanese Laid-open Patent Application Publication No. 2003-8814499, for example. Specifically, in the technique pertaining to Patent Document 1, two smoothing capacitors are connected in series to each other and are connected in parallel to the power supply. Moreover, a balancing resistor whose resistance value is smaller than those of internal resistors of the smoothing capacitors is connected in parallel to the smoothing capacitors. The balancing resistor is a resistor for maintaining a balance between the voltages applied to the smoothing capacitors so that the voltages applied to the smoothing capacitors fall within the rated voltage of the capacitors.
Further, as a related technology other than Japanese Laid-open Patent Application Publication No. 2003-8814499, there is the technology disclosed in Japanese Laid-open Patent Application Publication No. 1-169516.